Printed web ribbon registration control system

ABSTRACT

This control system maintains proper registration of several continuously advancing printed web ribbons, which are to be gathered in superimposed relationship and then perforated, cut and folded along lines located in unprinted spaces between successive printed areas. Each ribbon, while under substantially constant tension, enters an individual control nip whose velocity is corrected in accordance with the detection there of misregistration of the ribbon with respect to a reference pulse. A further correction is provided by changing the phase of this reference pulse with respect to the perforating device in accordance with ribbon misregistration at the perforating device. This latter correction is not made during every cycle of operation and it is not made unless the misregistration exceeds an acceptable minimum.

United States Patent [72] Inventor JamesN. Crum 3,097,844 7/1963 Huck270/52 Chagrin Falls, Ohio 3,280,737 10/1966 Huck.... 226/X {21] Appl.1N0. 754,196 3,326,436 6/1967 Huck 226/44X 22 F1 d A 21,1968 E ai 19,1971 :nmaryExzmmer-aLawrence Charles [73] Assignee Harris-lntertypeCorporation Home) ynn and Taro! Cleveland, Ohio a corporation ofDelaware ABSTRACT: This control system maintains proper registra- [54]PRINTED WEB RIBBON REGISTRATION tion of several continuously advancingprinted web ribbons, CONTROL SYSTEM which are to be gathered insuperimposed relationship and 37 chimsbsnrawing Figs then perforated,cut and folded along lines located in unprinted spaces betweensuccessive printed areas. Each ribbon, [52] US. Cl 270/52, while underSubstantially constant tension, enters an 226/28 dividual control nipwhose velocity is corrected in accordance [51] Int. Cl B65h 43/00 withthe detection there f miSregiSn-ation f the ribbon with Field of Search3023353; respect to a reference 1 A f th correction is provided 1 i i bychanging the phase of this reference pulse with respect to Referencescued the perforating device in accordance with ribbon misregistration atthe perforating device. This latter correction is not UNITED STATESPATENTS made during every cycle of operation and it is not made unless2,873,1 l7 2/1959 Crosfield et a1 r. 226/28 the misregistration exceedsan acceptable minimum.

PATENTED JAN19I97I 3155 509 sum 1 or e INVENTOR. JAMES M CRUM BY yaw/zF4 yA/M #244010 PATENTEU JAN] 9 l97l sum-2 UF 6 IN VENTOR.

JAMEJ' M CRUM PATENTEU JAN] 9191: 355 509 sum 3 [1F 6 PATENTEI] JAN 1 9|97| saw 5 [IF 6 u ew TR Nam w INM M, W Ma w /77' 7' ORA/6 1 3 PRINTEDWEB RIBBON REGISTRATION CONTROL SYSTEM This invention relates to aregistration control system for printed webs.

In certain practical applications of web presses, a relatively wideprinted web coming out of the press is slit longitudinally into two ormore ribbons, each having a series of printed areas in succession alongits length which are separated by smaller unprinted spaces. After beingslit, the ribbons are advanced continuously to gathering cylinders wherethey are superimposed upon each other in sandwichlike fashion in apredeter mined order. The gathered ribbons are then advanced toperforating and cutoff cylinders, where alternate unprinted spacesbetween successive printed areas are perforated and severed,respectively. The gathered ribbons are cut into lengths corresponding tohalf the circumference of the impression cylinder, and each cut lengthof the ribbon has a transverse perforated line midway along its length.The respective perforating and cutoff cylinders are driven from thepress drive, as are the web ribbon drive rollers. Ideally, eachrevolution of the perforating cylinders and each revolution of theeutoff cylinders should correspond to movement of a predetermined lengthof the web ribbons so that the web ribbons will be perforated and cutoffat predetermined locations in alternate unprinted spaces between theprinted areas. In practice, however, this ideal is difficult to achieveand it is an important purpose of the present invention to provide anovel and improved control system for insuring proper registration ofthe web ribbons with respect to a cyclically operated mechanism whichacts on the gathered ribbons, such as a perforating mechanism and/or acutoff mechanism.

It is an object of this invention to provide a novel and improvedregistration control system for regulating the speed of an advancing webmember with respect to a cyclically operated mechanism into which theweb member is fed.

Another object of this invention is to provide a novel and improvedcontrol system for regulating the velocities of two or more individualprinted web ribbons to insure their proper registration with respect toeach other and with respect to a cyclically operated mechanism.

Another object of this invention is to provide such a system in whicheach web ribbon passes through an individual control nip whose velocitymay be advanced or retarded substantially in accordance with an errorfactor equal to the sum of twice the misregistration in the presentcycle of operation of the cyclically operated mechanism plus thesummation of the misregistrations in previous cycles of operation.

Another object of this invention is to provide such a system whichsenses the misregistration of the gathered ribbons close to thecyclically operated mechanism and, if this misregistration exceeds atolerable minimum value, a phase correction may be applied for reducingthe misregistration of the gathered ribbons with respect to thecyclically operated mechanism.

Another object of this invention is to provide such a system in whichthe phase corrections resulting from the detection of misregistration ofthe gathered ribbons near the cyclically operated mechanism do notinteract with the control nip velocity corrections for the individualribbons to produce system instability.

Further objects and advantages of this invention will be apparent fromthe following detailed description of a presently preferred embodiment,which is illustrated schematically in the accompanying drawings, inwhich:

FIG. 1A is a schematic perspective view of a printed web coming from aprinting press into a slitter which slits the web longitudinally intofour ribbons;

FIG. 1B is a schematic perspective view showing the four web ribbonspassing through a ribbon drive system in accordance with the presentinvention;

FIG. 2 is a schematic diagram illustrating the complete control systemof the present invention as applied to two of the web ribbons;

FIG. 3 is a schematic block diagram illustrating. part of one of thecontrol nip velocity correction computers in the present control systemand pulse timing charts for this part of the control system;

FIG. 4 is a schematic block diagram illustrating the remainder of thiscontrol nip velocity correction computer;

FIG. 5 is a schematic block diagram illustrating the phase correctioncomputer in the present system for regulating the phase of the variablephase pulse generator and hence the velocity of all control nips to tendto eliminate any misregistration detected near the perforatingcylinders;

FIG. 6 is a table showing the operation of the control nip correctioncomputer over several cycles of operation in response to an arbitrarilyselected open loop error; and

FIG. 7 shows the open loop error, the correction applied and the actualerror, all plotted against the number of cycles of operation, inaccordance with the FIG. 6 table.

WEB RIBBON DRIVE SYSTEM FIGS. 1A and 13 Referring to FIG. 1A, a printedweb W coming from the chill rolls 10, ll of a printing press is slitlongitudinally by a slitter S into a series of parallel, side-by-sideribbons, here shown as the four ribbons W-l, W-2, W-3 and W-4. Themodulus of elasticity of the web W may be different at differentlocations across its width, so that the modulus of elasticity of oneribbon, W-l for example, may differ from that of one or more of theother ribbons W-Z, W-3 and W-4.

From the slitter the four ribbons pass in separate paths into the drivesystem shown in FIG. 18. Considering only the web ribbons W-l, thisribbon passes down over a fixed guide roll 15 and then in a loopextending under a constant tension device, which is shown schematicallyas a weighted roller 16, and then up over another fixed guide roll 17.From the latter the ribbon W-l passes to a control nip provided by apair of drive rollers 20 and 21, which are driven through a differentialfrom the press drive. All of the guide rolls turn freely.

The constant tension roller 16 is floatingly supported and is loaded bymeans of an air cylinder (not shown), which urges roller 16 downwardwith a predetermined constant force. When in equilibrium, the forceproduced by the air cylinder is equal and opposite to the force producedby tension in the ribbon. Equilibrium can only be obtained when thecontrol nip drive rollers 20 and 21, are driven at a specific speed:

If the speed of the controlhip drive rollers is Eiifiirn iricreased, theconstant tension roller will move in a direction to shorten the looppath of the ribbon between guide rolls l5 and 17. A temporary decreasein control nip drive roller speed will cause the loop path to lengthen.

Each of the other ribbons W-2, W-3 and W-4 advances through a similarconstant tension drive arrangement to a respective control nip.Corresponding elements of the drive arrangement for each of theseribbons are given the same reference numerals as those for the firstribbon, W-l, but with a suffix added which designates the ribbon, Forexample, the

constant tension roller for ribbon W-2 is identified by the designationl6-2. The detailed description of the ribbon drive will not be repeatedfor each of ribbons W-2, W-3 and W-4. It should be understood that eachof these ribbon drives operates on the same principles as explained, andto be further explained hereinafter, for ribbon W-l.

From their individual control nips the respective ribbons W- l, W-2, W-3and W-4 advance through equal distances to a pair of gathering cylinders22 and 23, which guide the ribbons into face-to-face, superimposed orsandwiched relationship. The superimposed ribbons then move between apair of confronting perforating cylinders 24, 25, one of which carriestwo diametrically opposed, serrated blades 26 which perforates all ofthe superimposed ribbons twice for each revolution of the perforatingcylinders.

The superimposed ribbons then move between a pair of pull rolls l2 andfrom there the superimposed ribbons pass between a pair of confrontingcutoff cylinders 13 and 14, one of which carries two diametricallyopposed blades 13a which sever all of the superimposed ribbons twice foreach revolution of the cutoff cylinders.

The perforating cylinders 24, 25 and the cutoff cylinders 13, 14 aredriven from the press drive.

Each ribbon has a plurality of successive identical printed impressions,each having four successive different printed areas in successionlengthwise of the ribbon. The printed areas are spaced-apart insuccession along its length by much shorter unprinted spaces between theprinted areas. A register mark is printed in every other unprinted spaceto determine the location where the ribbon is to be perforated by theperforating blade 26, as explained hereinafter. The cutoff blade 13a oncutoff cylinder 13 severs the ribbon at each of the remaining unprintedspaces between printed areas on the ribbon. The peripheral orcircumferential length of each perforating cylinder and each cutoffcylinder is substantially equal to the ribbon length of a printed areaplus the next adjoining unprinted space, so that one revolution of theperforating and cutoff cylinders takes place during the advance of oneimpression length of the ribbon (or four printed areas).

In accordance with one aspect of the present invention, the passage ofone ribbon register mark per impression is sensed near the control nipand its actual instantaneous position is compared with the instantaneousposition it should have with respect to the perforating cylinder blade26 in order that the ribbon will be perforated at the desired locationin the unprinted space between alternate printed areas. Any differencebetween the actual position of the register mark and its desiredposition is used to temporarily increase or decrease the velocity of thecontrol nip for that ribbon so as to reduce or eliminate thisdifference, or positional error, by changing the position of theconstant tension device 16. Each printed impression on the ribbon shouldcorrespond to one revolution of the perforating and cutoff cylinders.

CONTROL SYSTEM FIG. 2

Referring to FIG. 2, the lower control nip roller 21 for each ribbon isdriven from the gear train of the press through a respectivedifferential 27. Each differential 27 is controlled by a respectivestepping motor 28 which is arranged, through circuitry to be described,to receive correction pulses so as to increase or decrease the speed atwhich the control nip is drive iii aebraaaaawmrsh im oinarasga tion.tobe explained in detail hereinafter.

At each control nip a respective photoelectric sensor 29 senses theregister mark on the respective ribbon as it moves past, and the sensordelivers a register mark pulse over line 30 to one input terminal of aribbon control nip velocity correction computer 31. This computer alsoreceives a reference pulse on a second input line 32 from a variablephase pulse generator 33 which operates in synchronism with the rotationof the perforating cylinders 24 and 25.

Ideally, the reference pulse on line 32 should coincide in time with theregister mark pulse on line 30. In that case, the

of the present men:

register mark read by the sensor 29 is correctly positioned andtherefore the control nip velocity for that ribbon is correct.

However, if the pulses on lines 30 and 32 do not occur at the same time,this means that the register mark just read from the ribbon is out ofregistration. Such noncoincidence will be sensed by the correctioncomputer 31, which will cause a temporary change in the number ofcorrection pulses to be applied to the stepping motor 28 to cause thecontrol nip velocity for that ribbon to be temporarily increased ordecreased to a value which is effective to reduce or eliminate thismisregistration.

It should be understood that each of the other web ribbons W-2, W-3 andW-4 has an identical control arrangement, including an individualcontrol nip which is driven through an individual differential from thepress drive and with each differential controlled by an individualstepping motor. A separate photoelectric sensor is provided at thecontrol nip for each ribbon to sense the movement of the ribbon registermark past it. The output of this sensor is connected to one input of anindividual control nip velocity correction computer, which has a secondinput connected to the perforator cylinder-operated pulse generator 33.

As already stated, the distances between thecontrol nips and thegathering cylinders 22, 23 are equal, preferably.

The pull rolls 12 are driven from the press drive either through aconstant torque mechanism 34, such as a constant torque clutch, orthrough an adjustable speed ratio device. In the former case, thegathering rolls 22, 23 produce a constant tension on the gatheredribbons.

In the latter case, the pull rolls produce a tension on the gatheredribbons as follows:

V,, circumferential velocity of chill rolls, inches per second,

T tension of the gathered ribbons, pounds per inch of ribbon width.

In either case, the stretch per unit length of each of the ribbons inthe region between its control nip and the pull rolls 12 will be thesame. Since the lengths of the ribbons between the respective controlnips and the pull rolls 12 are equal, if one of the ribbons is in properregistration, both at the perforating cylinder and at the ribbon controlnip, and if all the other ribbons are in correct registration at theirrespective control nips, then all ribbons will be in correctregistration at the perforating cylinders 24 and 25.

Before proceeding with the description of the details of the controlcircuit for each control nip, the factors involved in correcting theribbon speed will be explained. i

For each printed impression on the ribbon, the measured instantaneousdifference between the actual position of the following register mark asit passes the photoelectric sensor "29 and its desired position toprovide exact registration with respect to the perforating blade 26 maybe specified as the error distance, E, which is equivalent to a certainnumber of correction pulses into the stepping motor 28. That is, if itwere possible to apply these correction pulses instantaneously to thestepping motor and thereby instantaneously change the control nip speedmomentarily, the detected error would be eliminated.

However, the correction cannot be made instantaneously, and merelyapplying the number of correction pulses equivalent to the errordistance, E, during a single cycle of operation would not necessarilybring the ribbon back into correct registration because it would notinsure that the correction would catch up to the error.

In accordance with the present invention. correction pulses, C,,, areapplied to the stepping motor 28 in accordance with the followingrelationship:

where E,, is the misregistration error measured at the end of summationof the individual misregistration errors measured at the end of everypreceding cycle of operation up to and including the immediatelypreceding (n-l) cycle, and C,, is the number of correction pulses whichare to be applied to the stepping motor in the next (n+1) cycle ofoperation.

As described hereinafter, during any given cycle of operation (equal toone revolution of the perforating and cutoff cylinders) the correctioncomputer 31 for each control nip will apply to the stepping motor 28, inresponse to the sensing of a ribbon register mark by the sensor 29 atthat control nip, a number of correction pulses sufficient to providethe correction C, as stated by the foregoing equation (1). Thesecorrection pulses will cause the stepping motor to correct the controlnip speed by the sum of the previous misregistration the present (n)cycle of operation, is the n-l errors Ek)- plus twice the present.misregistration error (2E,,), in accordance with the foregoing equation(I). By this correction, the control nip speed is regulated tomomentarily speedup or slowdown the ribbon to compensate for the presentmisregistration and to establish a relatively steady state ribbon speedwhich will maintain a predetermined tension on the ribbon, so that theconstant tension roller 16 will remain at a corresponding predeterminedlevel and the ribbon path length through the loop at the constanttension roller will remain substantially constant.

The table of FIG. 6 and the graph of FIG. 7 show the operatron of thiscontrol system under an arbitrarily assumed open loop error situation.As can best be visualized from FIG. 7, the actual error, E,,, isminimized as a result of the correction pulses C applied in accordancewith equation l above.

CONTROL NIP VELOCITY CORRECTION COMPUTER FIG. 3

Referring to FIG. 3, the dashed-line enclosure 31a contains thecomponents of the correction computer 31 (FIG. 2) for the control nip.The unprinted space (where the register mark appears) between successiveprinted areas on the ribbon is only a small fraction of the length ofthe total printed impression on the ribbon. The photoelectric sensor 29should be disconnected from the control nip velocity correction computerwhile any printed area is moving past the sensor; otherwise, thecomputer might respond to an output signal from the sensor caused by itsreading the printed area, whereas the purpose of the sensor is merely tosense the movement of a registration mark past it.

For this purpose, as shown in FIG. 3, the sensor 29 is connected by line30 to a gate circuit which is normally closed. The gate circuit 35 canbe opened only during the small fraction of each revolution of theperforating and cutoff cylinders when the unprinted space betweencertain printed areas in the correspondingprinted impression on theribbon is moving past the sensor 29. This open period of gate circuit.35 will be referred to as the window period.

One of the perforating cylinders 25 drives an analog-todigital encoder36 having two different outputs, one of which produces a single outputpulse on line 37 for each revolution of the perforating cylinders. andthe other of which produces 240 evenly spaced pulses on line 38 for eachrevolution of the perforating cylinders. The timing or phaserelationship of the pulses on lines 37 and 38 with respect to therotation of cylinder 25 can be varied as explained hereinafter in thedescription of FIG. 5.

Referring to the pulse timing charts of FIG. 3. line a shows theregister mark which occurs in the middle of each printed impression, inthe unprinted space between two successive printed areas on the ribbon.The single encoder output pulse on line 37 (line b) occurs at a time,1,, somewhat ahead of this register mark. This pulse on line 37 isapplied to the open" control terminal 39 of gate circuit 35. causingthis gate circuit to open. The gate circuit will remain open until apulse appears at its close" control terminal 40, which is connected tothe 240 pulse-per-revolution encoder output line 38 through twoseries-connected divider circuits 41 and 42, each of which produces asingle output pulse for every two input pulses it receives. With thisarrangement, the fourth pulse occurring on line 38 following the singlepulse on line 37 will be applied to the *close" terminal 40 of gatecircuit 35, resetting the latter to its normal closed condition. Thisclosing of the gate circuit occurs at time L as indicated at line c ofthe FIG. 3 pulse timing chart. The gate circuit 35 will remain closeduntil the next pulse appears on line 37, i.e., during the nextrevolution of the perforating cylinders 24, 25.

It will be apparent that the gate circuit 35 is open only during a smallfraction (4/240) of each revolution of the perforating and cutoffcylinders.

The gate circuit 35 also has a reference pulse input terminal 43 whichis connected to the output of the first divider 41. With thisarrangement, the second encoder output pulse which appears on line 38after the single encoder output pulse appears on line 37 will be appliedto terminal 43. This is the reference pulse against which the registermark pulse from sensor 29 is compared. This reference pulse is shown atline at of the FIG. 3 pulse timing chart as occurring at the midwaypoint of the window period of gate circuit 35 (between times t, and rLine 2 of the FIG. 3 pulse timing chart shows the error period, which isthe time interval between the leading edge of the register mark pulse(line a) and the leading edge of the reference pulse (line d). Theregister mark pulse (line a) will occur sometime between times t, and tnormally, and it may occur either before or after the reference pulse,depending upon whether the misregistration is lagging or leading, or itmay occur simultaneously with the reference pulse if there is nomisregistration at all. The horizontal width of the error period (linee) represents the timing error of the register mark.

In practice, the press may run at speeds of from to 1500 feet perminute. Therefore, the magnitude of the timing error between theregister mark pulse and the reference pulse will be a function of thepress speed. This timing error must be converted to terms of absolutedistance, i.e., fractional inches of error of the reference mark on theweb.

In the preferred embodiment of the present system this is accomplishedin a simple and inexpensive manner by providing a DC tachometer 44driven by the perforating cylinder 25 and having its output connected toa voltage-to-frequency converter 45. This converter produces a series ofrelatively high frequency output pulses at a frequency which isproportional to the DC voltage output of the tachometer, which in turnis proportional to the rotational speed of the perforating cylinders 24,25 and the press speed. For example, at the assumed maximum press speedof 1500 feet per minute, the converter pulse rate is 350 kilocycles persecond, so that each output pulse which converter 45 producescorresponds to approximately .000857 inch of ribbon error ormisregistration.

These error pulses are applied continuouslytoarfihputterminal 46 of thegate circuit 35, but, as shown at line f of the FIG. 3 pulse timingchart, they pass through the gate circuit 35 only during the errorperiod (line e). The number of error pulses passed by the gate circuit35 will be a function of the time duration of this error period and ofthe press speed, as explained. Therefore, the number of these errorpulses will be proportional to the actual misregistration or distanceerror of the registration mark on the ribbon.

The gate circuit 35 preferably consists of integrated circuit logicunits which perform the following logic operations:

1. If. during the window period. the gate circuit receives aregistration mark pulse from sensor 29 it maintains a logic 1 conditionon output line 47 to indicate that the registration mark has beenobserved by the sensor;

during the error period. it passes error pulses from its finlet terminal46 to its outlet line 48 equal in number to 2E,, in equation lhereinbefore;

"lag" outlet line 50. depending upon whether the misregistration orpositional error of the register mark on the ribbon is leading orlagging.

Each ribbon nip correction computer 31 includes a pair of bidirectionalcounters 51 and 52 interconnected by parallel entry circuitry 53.

Counter liis the error summation counter for keeping the n-l count ofthe term 2 E in equation (1). Counter 51 has a count input terminal 54connected to the 2E,, output line 48 of gate circuit 35 through adivider 55, which divides by two. With this arrangement, the counterinput terminal 54 receives every second pulse appearing on line 48 andtherefore the number of pulses applied to terminal 54 during anyparticular cycle of operation is equal to E,, in equation (I) for thatcycle. Counter 51 performs the summation of all the previous errors andit is never reset.

Counter 51 also has a pair of control terminals 56 and 57 which areconnected respectively to the lead and lag output lines 49 and 50 fromgate circuit 35. The lead or lag output signal from the gate circuittells counter 51 to count up or down, as the case may be.

The lower counter 52 has a pair of control terminals 58 and 59, whichare connected respectively to the lead and lag lines 49 and 50, so thatthe lead or lag output signal from gate circuit 35 tells the counter 52to count up or countdown.

The lower counter 52 has two different count inputs:

1. it receives the count stored in the error summation counter 51 forall of the previous cycles of operation through the parallel entrycircuit 53 at the beginning of the window period;

. during the error period portion of the window period (line e of theFIG. 3 pulse timing chart) it receives the 2E,, 7 error pulses for thepresent cycle of operation from the gate circuit output line 48 by wayof its serial entry input terminal 60. Therefore, at the end of thewindow period the counter 52 has received the previous error and it hasreceived the count, 2E, of twice the error for the present cycle ofrevolution of the cutoff cylinders. These two counts are added bycounter 52 to provide the i summation count, from counter 51,

according count, to

out of counter 52 during the interval between window periods, as will beexplained later.

At the beginning of the next window period. counter 52 is m n1 reset tothe new 2 k count which is now stored in the error summation counter 51,which is different from the previous error summation count by the amountof the error it delivers a signal to either its "lead" output line 49 orits nl count. E in the cyclejust ended. Added to this new 2 E count incounter 52 is the 2E, which will occur in the error period portion ofthe window periodjust begun.

CONTROL NIP VELOCITY CORRECTION COMPUTER FIG. 4

The correction pulses which are applied to the stepping motor 28 for thecontrol nip for ribbon W-l are derived from the 240 pulse perimpression'out'put of the' encoder 36 during the major portion of eachcycle outside the window period shown at line 0 of the FIG. 3 ptilsetiming chart. Referring to FIG. 4, the 240 pulse per impression encoderoutput line 38 is connected to a divider 70, which divides by four, sothat for every four pulses on its input line 38 the divider passes asingle pulse to its output line 71. Line 71 is connectedto the input ofa normally closed gate 72 having an output line 73 connected to theinputs of a pair of gates 74 and 75 for clockwise and counterclockwiserotation of the stepping motor 28 for ribbon W-l, respectively. Theoutputs from these gates are both connected to the input of a translator76 of known design which produces a rotation of the stepping motor 28proportional to the number of input pulses it receives from either gate74 or gate 75 and in a direction determined by whether these pulses arereceived from the clockwise gate 74 or the counterclockwise gate 75.

The output line 73 of gate 72 is also connected to the serial n1 entryinput terminal 60 of the 2E +2 Ek counter 52. This connection is madethrough a divider 77, which divides by two the number of pulses comingfrom the gate 72..The reason for this is to match the resolution of thecount stored in-counter 52 to the correction provided by each steppingmotor pulse. The correction pulses from gate 72 which are appliedthrough the divider 77 cause the counter 52 to count down toward zerofrom the count stored therein.

Since the operation of the system is intended to minimize the positionerror of the register mark on the ribbon, it is also intended tominimize the count stored in counter 52.

If this count ever reaches zero, which means that the register mark onthe ribbon is in perfect registration, this occurrence would be detectedby a zero coincidence portion of a coincidence circuit 78 associatedwith counter 52, which would then apply a pulse to its outlet line 79 toclose the gate 72. The closing of gate 72 would prevent any morecorrection pulses from being applied to the stepping motor 28 (throughthe translator 76) or to the counter 52.

As long as the count C stored in counter 52 is positive (i.e., greaterthan zero), then the coincidence circuit 78 applies a pulse to itsoutput line 80 to open the clockwise gate 74 and also to energize thecount down control terminal 59 of counter 52.

Conversely, as long as the count stored in counter 52 is negative, thenthe coincidence circuit 78 applies a pulse to its output line 81 to openthe counterclockwise gate 75 and also to energize the count up controlterminal 58 of counter 52.

In FIG. 4 the register mark detection circuit 82 is part of the gatecircuitry 35 in FIG. 3. This detection circuit receives an input pulsefrom the photoelectric sensor 29 for ribbon W-l via input line 30 inresponse to the sensors detection of a registration mark on this ribbon.This happens once during each revolution of the perforating cylinders,i.e., once for each printed impression on the web. This input pulsecauses the register mark detection circuit 82 to maintain a logic 1condition via its output line 47 to open the gate 72. If no registrationmark on the ribbon W-l is detected during a given cycle of operation,line 47 will go to logic 0 and the gate 72 will remain closed, therebypreventing any correction pulses from being 9 applied to the steppingmotor 28 for ribbon W-l until after the next registration mark isdetected. In addition, if no registration mark is detected, this circuitcauses transfer of a relay Contact which is used to lock up the constanttension roller 16 for ribbon W-l.

Once during each cycle of operation the gate circuit 35 forms a windowpulse as was described earlier. During this window period, gate circuit35 produces a signal on its output line 47 which causes gate 72 toclose.

There is a practical upper limit on the number of correction pulseswhich can be applied to the stepping motor 28 during a single revolutionof the perforating and cutoff cylinders; otherwise. the web tensionmight be high enough to cause the web to break. In one practicalembodiment of this invention, the maximum advance or retardation of theribbon which the stepping motor will be permitted to provide is 0.05inch per impression. In this embodiment, for the particular gearingratios used with the stepping motor, this maximum advance or retardationwould require 59 correction pulses per impression to the stepping motor.

These correction pulses are applied to the stepping motor 28 for ribbonW-l only during the major portion of each cycle outside the windowperiod shown at line c of the FIG. 3 pulse timing chart. Since thiswindow period occupies no more than 4/240 of each cycle, only one ofeach 60 pulses per cycle appearing on line 71 in FIG. 4 will be blockedby gate 72 during the window period. Assuming that gate 72 is reopenedby the detection of a register mark and by a large misregister error,the remaining 59 pulses for this cycle will pass through gate 72 to line73. Consequently, the translator 76 for the stepping motor 28 canreceive as many as 59 pulses'per printed impression if themisregistration exceeds a certain value. The misregistration can becorrected during a given cycle of operation only to the extent of these59 correction pulses.

Since there is a physical limit on the rate at which the web can beretarded or speeded up, which limits the number of correction pulses percycle for the stepping motor, the maximum count of each bidirectionalcounter 51 and 52 is similarly limited, preferably. For example, eachcounter may be limited to a maximum count of plus or minus 62. If thecounter is instructed to count beyond this, it simply stops counting andholds the maximum count which it is capable of accepting. Consequently,if there is a very large misregistration, the stepping motor 28 will runat its maximum rate of 59 correction pulses per second for enoughimpressions until the error is reduced enough to bring the count incounter 52 below the maximum number. This feature minimizes theovershoot which would otherwise occur if the counter capacity were notlimited to approximately match the maximum correction per impression.

The control nip for each of the other ribbons W-2, W-3 and W4 isprovided with an individual stepping motor 28-2, 28-3 and 284. Each ofthese stepping motors is controlled individually by a control nipvelocity correction computer' identical to that just described in detailwith reference to FIG. 4.

PHASE CORRECTION CONTROL FIG. 5

timing chart) which isapplied to the input of each ribbon nip correctioncomputer 31 during each window period. The time difference between theleading edge of this reference pulse and the leading edge of theregister mark pulse is the error period for that ribbon nip.

The variable phase reference pulse generator 33 is controlled by theperforating cylinder 25 such that at a predetermined rotational positionof the perforating cylinder 25 it causes the variable phase pulsegenerator 33 to deliver an output pulse via line 32 to the respectivecontrol nip correction computers for the individual ribbons. The phaserelationship of the variable phase reference pulse generator 33 withrespect to the position of the perforating cylinder may be modified by astepping motor 128 (FIG. 2). The stepping motor 128 can either advanceor retard the timing of the reference pulse produced by variable phasepulse generator 33. as explained hereinafter.

The operation of the stepping motor 128 is under the control of a phasecorrection computer 131 which is similar in many respects to thealready-described ribbon nip correction computer 31. Correspondingelements of the phase correction computer 131 are given the samereference numerals plus as the elements of the ribbon nip correctioncomputer 31, and the complete description of these elements will not berepeated.

Before proceeding with the description of the phase correction computer131, shown in the dashed-line enclosure in FIG. 5, it will be recalledthat the purpose of each of the individual ribbon nip correctioncomputers 31 is to regulate the individual ribbon nip velocity so thatthe registration mark on each ribbon will appear at the nip at thecorrect time with respect to the rotational position of the perforatingblade 26. This should bring the corresponding registration marks on theseveral ribbons into synchronism with each other at the individualribbon nips, and they should be in precise registration with each otherwhen they reach the perforating cylinders.

However. because of the physical spacing between the individual ribboncontrol nips and the perforating cylinders 24, 25, modulus changes inthe paper can cause the ribbons as a group to be out of registrationwith respect to the rotational position of the perforating blade 26 bythe time the grouped ribbons reach the perforating cylinders. Normally,any misregistration error of this sort will occur gradually, rather thanabruptly.

In accordance with the preferred embodiment of the present invention,the phase correction of the reference pulse generator 33 will beperformed:

I. only if the misregistration error at the perforating cylindersexceeds a predetermined acceptable minimum (e. g., 0.005 inch); and

2. only during one out of several cycles (e.g., one out of 10).

The purpose of these limitations is to minimize the possibility ofsystem instability which might occur if every misregistration detectedat the perforating cylinders were to cause a correction of the variablephase reference pulse generator 33 which in turn would cause acorrection of control nip velocities for the individual ribbons.

The phase correction computer 131 is controlled by a photoelectricsensor 129 which senses the registration mark on the ribbon W-4 as thegathered ribbons pass from the gathering cylinders 22, 23 toward theperforating cylinders 24, 25. Preferably, the sensor 129 is located asclose as possible to the perforating cylinders.

Referring to FIG. 5, the phase correction computer 131 includes a gatecircuit 135 similar to the already-described gate circuit 35 in theribbon nip correction computer 31. Gate circuit 135 is connected to theregistration mark sensor 129 through line 130.

This portion of the system includes a fixed phase pulse generator whichprovides one reference pulse per revolution of the perforating cylinders24, 25. To this end, the encoder 36 delivers to its output line 142 asingle pulse whose timing is dependent entirely upon the rotationalposition of the perforating cylinder 25, such that this fixed phasereference pulse will always occur at the same instant during eachrevolution of the perforating cylinders. This fixed phase referencepulse is applied to the reference terminal 143 of gate circuit 135.

Coincidence of the fixed phase reference pulse with the register markpulse observed by the perforating cylinder sensor 129 indicates correctregistration of the register mark with the perforating blade 26.

The already-mentioned analog-to-digital converter 36 is driven by theperforating cylinder to produce a single pulse each revolution on line137 and 240 pulses per revolution on 138. In contrast to the fixed phasepulse on line 142, the, timing of the pulses on lines 137 and 138 can beadjusted withrespect to the rotational position of the cutoff cylinder25. Consequently, the pulses on lines 137 and 138 will be referred to asvariable phase pulses. Line 137 is connected to a control terminal 139of gate circuit 135 to begin the window period of gate 135 at apredetermined time during each cycle of operation. while the unprintedspace between the printed areas on each ribbon is passing theperforating cylinder sensor 129. Line 138 is connected to the inputtermipal 2 00 of a counter 201 which delivers a window close' puls'e tothe control terminal 140 of gate circuit 135 in response to the fourthpulse on line 138 following the window open pulse on line 137.

The already-mentioned DC tachometer 44 and the voltageto-frequencyconverter 45 cause high frequency output pulses to be applied to theinput terminal 146 of gate circuit 135. The pulse frequency isproportional to the speed of the perforating cylinders which, as alreadyexplained, is proportional to the press speed.

With this arrangement (similar to the operation of the gate circuit inthe correction computer 31 for each individual ribbon nip), once duringeach revolution of the perforating cylindersthe normally closed gatecircuit 135 is opened when a pulse appears on the output line 137 ofencoder 36. Gate circuit 135 remains open until the fourth followingpulse appears on line 138, which will happen at not more than 4/240 of arevolution later. The time interval between the opening and closing ofgate circuit 135 is referred to as the window period.

The fixed phase reference pulse on line 142 will occur during thiswindow period.

During this window period, the time difference between the occurrence ofthe fixed phase reference pulse at terminal 143 of gate circuit 135 andthe occurrence of the registration mark pulse on line 130 produces theerror period during which the gate circuit 135 passes the error signalpulses coming from the voltage-to-frequency converter 45. The number oferror pulses passed by the gate circuit 135 depends upon the time difference between the fixed phase reference pulse on line 142 and theregistration mark pulse on line 130, as well as upon the press speed.Consequently, the number of error pulses passed by the gate circuit 135is a measure of the distance error or misregistration of theregistration mark on ribbon W- 4 as the gathered ribbons pass betweenthe perforating cylinders.

These error signals produce a control signal on either the lead"outputline 149 leading to gate 174 or the lag" output line 150 leadingto gate 175. Gates 174 and 175 are connected to a translator 176 toprovide clockwise and counterclockwise rotation, respectively, of thestepping motor 128. Both gates' 174 and 175 are normally closed, andneither opens until it receives a control signal on line 173 from gate172. Consequently, the error signals coming from the gate circuit 135(whether leading or lagging) cannot be applied to the translator 176 forthe stepping motor 128 unless gate 172 is open.

Gate 172 is under the control of a counter 202 which receives, via line148, the error signal pulse output from gate circuit 135. The pulseoutput from counter 202 goes into a latch device 203 having its outputconnected via line 204 to the gate 172. If during any cycle of operationthe error pulse input to the counter is less than 6, the latch 203 willmaintain gate 172 closed. However, if the error pulse count is 6 ormore, the latch 203 will apply a gate-opening signal to line 204. Thisinsures that gate 172 will open only if the misregistration is in excessof a predetermined tolerable minimum value, corresponding to 6 errorpulses.

The counter 202 is reset to zero and the latch 203 is reset to itsnormal gate-closing condition once during each cycle of operation, whenthe single encoder'pulse appears on line 137, which is connected to areset control-terminal205 of counter 202 and to a reset control terminal206 oflatch 203.

The opening of gate, 172 is alsounder the control of line 147, whichreceives a gate-opening-signal during each cycle of operation only ifthe registration mark-on the ribbon has been detected by sensor 129. 1

It will be understood that gate 172 will be opened only if agate-opening signal appears on linei-1.4-7,anda gate-opening signalappears on line 204. lfeither gateopeningsign al doesnot occur. thengate 172 will not open during that revolution of the cutoffcylinders.

ln add itipn gate 172 is controlled by a decade counter 207 having itsinput connected to the single pulse per cycle output line 137 fromencoder 36. The decade counter 207 delivers a gate-opening signal viaits output line 208 to gate 172 once for every 10 input pulses which itreceives from line 137-that is, only for one out of 10 cycles ofoperation (or revolutions) of the perforating cylinders 24, 25.Consequently, gate 172 can be opened only once in every 10 cycles, andeven then it will be opened only if a registration mark has beendetected (producing a gate-opening signal on line 147) and the errorsignal pulse count exceeds a predetermined minimum value (producing agate-opening signal on line 204).

After the end of the window period, the input pulse for the motor 128 isdelivered to gate 172 from counter 20]. As already stated, the signalinput to counter 201 is the variable phase 240 pulse per cycle signal online 138. The output of counter 201 is connected to a latch device 209,which passes this stepping motor pulse to the gate 172 after the sixth.-count on line 138 in each cycle of operation, which will be shortlyafter the end of the window period. Counter 201 and latch 209 are bothreset once each cycle by the single pulse appearing on line 137. I v

The single correction pulse passed by gate 172 is applied to thetranslator 176 for stepping motor 128 either through gate 174 or throughgate 175, depending upon whether the misregistration is leading orlagging. This correction pulse causes the stepping motor 128 to eitheradvance or retard the timingof the variable phase reference pulseproduced by the pulse generator 33, in the following manner:

The shaft of the encoder 36 carries a disc 211 having alternate opaqueand transparent regions. This disc is positioned between one or morelight sources 212 and photoelectric sensors 213 carried by a drum 214which is attached to the shaft 229 of the stepping motor 128. Thesensors 213 are connected to lines 137 and 138 to deliver, respectively,1 pulse per cycle of the perforating cylinders 24, 25 and 240 pulses percycle.

Normally (i.e., in the absence of an input pulse to the stepping motor128), the drum 214 is stationary, so that the light source or sources212 and the photoelectric sensors 213 have fixed positions and the 1pulse per cycle on line 137 and the 240 pulses per cycle on line 138will occur at fixed times during the revolution of the perforatingcylinder 25.

However, a pulse input to the stepping motor 128 will turn the drum 214so as to change the positions of the light source 212 and sensors 213,thereby changing the timing, or phase relationship, of the pulses onlines 137 and 138 with respect to the cyclic operations of theperforating cylinders.

Consequently, the beginning and the end of the window period for gatecircuit in the phase correction computer 31a can be varied in time, withrespect to the rotation of the perforating cylinders.

The pulse output lines 37 and 38 for the individual control nipcorrection computers 31 are also connected to the photoelectric sensors213, so that the timing or phase relationship of the pulses on theselines can be varied with respect to the cyclic operation of theperforating cylinders 24, 25. Therefore, the timing of the beginning andthe end of'the window period for the gate circuit 35 (FIG. 2) in thecorrection computer for each ribbon control nip will be changed inacv.ordarice with the correction provided by the stepping motor 528 inresponse to the detection of a positional error of the gathered ribbonsjust before they pass between the perforating cylinders. Also, theadjustment of the timing of the pulses appearing on line 38 varies thetiming of the reference pulse (line d of the HQ 3 pulse timing charts)whose leading edge occurs midway during the window period. Since thetime difference between this reference pulse and the register mark pulsedetermines the error period for the ribbon control nip in that cycle ofoperation, it will be evident that the phase (or timing) adjustmentprovided by the stepping motor 128 provides a correction for thevelocity of each ribbon control nip in response to the detectedmisregistration of the gathered ribbons just before they pass betweenthe perforating cylinders.

While a presently preferred embodiment of this invention has beendescribed in detail with reference to the accompanying drawings. it isto be understood that various modifications, omissions and adaptationswhich depart from the disclosed embodiment may be adopted withoutdeparting from the scope of the invention, as defined in the appendedclaims.

lclaim:

l. A registration control system for a web member passing through acontrol nip and from there into a cyclically operated mechanism, saidsystem comprising:

variable speed drive means operatively associated with the control nipto control its velocity;

sensing means operatively associated with the web member for sensing anypositional error of the advancing web member with respect to the cyclicoperation of said mechanism;

and correction means operatively associated with said variable speeddrive means to vary the speed of the control nip substantially inaccordance with an error factor equal to where E,, is the detectedpositional error of the web member in the present cycle of operation ofsaid mechanism;

n-l and 2 E is the summation of the positional errors of the web memberin previous cycles of operation.

2. A registration control system according to claim 1, wherein saidcorrection means comprises a first counter for -1 maintaining a count of2 iEk a second counter for receiving a count of 2E during each cycleofoperation of said cyclically operated mechanism and for receiving thecount stored in said first counter, and means for resetting said secondcounter after each cycle of operation of said cyclically operatedmechanism.

3. A registration control system for a plurality of printed web ribbonspassing through respective individual control nips and from there intosuperimposed relationship and thereafter into a cyclically operatedmechanism, said system comprising:

variable speed drive means operatively associated individually with therespective control nips to control individually the velocity of eachcontrol nip; sensing means operatively associated individually with eachweb ribbon for sensing any positional error of the advancing ribbon withrespect to the cyclic operation of said mechanism; and

correction means operatively associated with each variable speed drivemeans individually to vary the speed of the respective control nipsubstantially in accordance with an error factor equal to where E is thedetected positional error of the respective ribbon in the present cycleof operation of said mechanism,

and 2 E is the summation of the positional errors of the respectiveribbon in previous cycles of operation.

4. A registration control system according to claim 3, wherein saidvariable speed drive means for each control nip comprises a differentialand a stepping motor for varying the output speed of the differential inaccordance with the energization of the stepping motor.

5. A registration control system according to claim 3, wherein saidcorrection means comprises a first counter for maintaining a count of asecond counter for length which are separated by spaces having aregister mark therein, said control system comprising:

A plurality of pairs of confronting rollers providing control nips forthe respective web ribbons;

A variable speed drive means operatively associated individually witheach control nip to control the latter's velocity;

Means operatively associated individually with each web ribbon ahead ofthe respective control nip therefor for maintaining a substantiallyconstant tension on said web ribbon;

sensing means positioned near each control nip for sensing the movementpast it of each register mark on the respective web ribbon and forproducing a register mark pulse in response to said sensing of aregister mark;

gathering cylinders located after said control nips and operativelyassociated with the web ribbons to urge the latter into superimposedrelationship;

a cyclically operated mechanism located after said gathering cylindersand operatively associated with the superimposed web ribbons to act onthe latter at said spaces between the printed impressions;

means operated in timed relationship with the cyclic operation of saidmechanism for producing a reference pulse at a predetermined point ineach cycle of operation of said mechanism;

means for comparing the timing of said register mark pulse and saidreference pulse to determine any positional error of the respectiveregister mark on the web ribbon with respect to the cyclic operation ofsaid mechanism; and

correction means operated by said last-mentioned means and operativelyassociated with each control nip drive means individually to vary thespeed of the respective control nip substantially in accordance with anerror factor equal to the positional errors of the register marks on therespective ribbon in previous cycles of operation.

7. A registration control system according to claim 6, and furthercomprising a first counter connected to receive E, error pulses duringeach cycle of operation and operative to maintain a count of thesummation of all the error pulses for previous cycles of operation, asecond counter for receiving during each cycle of operation both thecount stored in the first counter at the end of the preceding cycle ofoperation and 2E,, error pulses for the present cycle of operation, andmeans for resetting said second counter at the end of each cycle ofoperation.

. from said correction means whenever the count stored in said secondCOUHII reaches zero.

10. A registration control system according to claim 8, wherein saidfirst and second counters receive their respective counts during theinterval in each cycle of operation while said space between successiveprinted areas on the respective ribbon is moving past said means forsensing the register mark thereon.

11. A registration control system according to claim 10, wherein'thecorrection pulses reduce the count stored in said second counter while aprinted area on the respective ribbon is moving past said means forsensing the register mark thereon.

12. A registration control system for a pluralityof printed web ribbonspassing through respectiveindividual control nips and from there intosuperimposed relationship and thereafter into a cyclically operatedmechanism, said system comprising:

variable speed drive means operatively associated in dividually with therespective control nips to control individually the velocity of eachcontrol nip;

sensing means operatively associated individually with each web ribbonnear the respective control nip for sensing any positional error of theadvancing ribbon thereat with i respect to the cyclic operation of saidcyclically operated mechanism;

correction means controlling each variable speed drive meansindividually and operable in response to said sensing means to vary thespeed of the respective control nip;

additional sensing means operatively associated with one of the webribbons near said cyclically operated mechanism for sensing a positionalerror of the superimposed ribbons with respect to the cyclic operationof said mechanism; and

means operated by said additional sensing means for varying theoperation of said correction means for each variable speed drive meansin accordance with said positional error of the superimposed webribbons.

13. A registration control system according to claim 12, wherein saidcorrection means varies the speed of the respective control nipsubstantially in accordance with an error factor equal to where E is thedetected positional error of the respective ribbon in the present cycleof operation of said cutoff n-l mechanism, and 2 )E is the summation ofthe positional errors of the respective ribbon in previous cycles ofoperation.

14. A registration control system according to claim 12, and furthercomprising means for preventing said last-mentioned means from varyingthe operation of said correction means except during certain cycles ofoperation of said cyclically operated mechanism.

15. A registration control system according to claim 14, and furthercomprising means for preventing said means operated by said additionalsensing means from varying the operation of said correction means exceptwhen said positional error of the superimposed web ribbons exceed apredetermined value.

16. A registration control system for a plurality of printed ribbonspassing into superimposed relationship and thereafter into a cyclicallyoperated mechanism, said system comprising:

means operatively associated individually with the respec tive ribbonsto control individually the velocity of each of the ribbons;

sensing means operatively associated individually with each ribbon forsensing any positional error of the advancing ribbon with respect to thecyclic operation of said mechanism;

means for determining for each of the r ibbons an error factor whichincludes a summation of the positional errors of the respective ribbonin previous cycles of operation of the mechanism; and

correction means operatively associated with each ribbon individuallyfor varying the speed of the respective ribbon in accordance with saiderror factor'which includes a summation of the positional errors of therespective ribbon in previous cycles of operation of said mechanism.

17. A registration control system according to claim 16, wherein eachribbon has a plurality of successive printed areas with spacestherebetween having a registration mark therein, and said sensing meansfor each ribbon comprises:

means for sensing the passing of a register mark on the respectiveribbon and for producing a register mark pulse in response thereto;

means operated in response to the cyclic operation of said mechanism forproducing a reference pulse at a predetermined point in the latterscycle of operation; and

and means for determining the magnitude of the detected positional errorof each ribbon for each cycle of operation said mechanism in accordancewith the time difference between said register mark pulse and saidreference pulse.

l8v A registration control system-according to claim 17, wherein saidlast-mentioned means comprises a normally closed gate circuit, means foropening said gate circuit in response to either said register mark pulseor said reference pulse and for closing the gate circuit in response tothe other of said pulses, and means for producing a series of pulseswhose frequency is proportional tothe speed of said cyclically operatedmechanism and for applying said last-mentioned pulses to said gatecircuit to pass through the gate circuit while the latter is open.

19. A registration control system according to claim 18, wherein saidmeans for producing a series of pulses comprises a tachometer driven bysaid cyclically operated mechanism for producing a voltage proportionalto the speed of the cyclic operation of said mechanism, and avoltage-to-frequency converter operated by said tachometer to generatesaid series of pulses at a frequency proportional to the voltageproduced by the tachometer.

20. A registration control system according to claim 16. wherein saiderror factor further includes at least the detected positional error ofthe respective ribbon in the present cycle of said mechanism, and saidcorrection means includes a first counter for maintaining a count of thesummation of the positional errors of the respective ribbon in previouscycles of operation of said mechanism, a second counter for receiving acount of at least the detected positional error of the respective ribbonin the present cycle of said mechanism during each cycle of operation ofsaid cyclically operated mechanism, and means for resetting said secondcounter after each cycle of operation of said cyclically operatedmechanism.

21. A registration control system for a plurality of printed ribbons.each having printed areas in succession along its length which areseparated by spaces having a register mark therein, said control systemcomprising:

a plurality of rollers operatively associated with each ribbon tocontrol the velocity of the associated ribbon;

sensing means positioned near each of the respective ribbons for sensingthe movement past it of each register mark on the respective ribbon andfor producing a register mark pulse in response to said sensing of aregister mark;

gathering cylinders located after said rollers and operativelyassociated with the ribbons to urge the latter into superimposedrelationship;

a cyclically operated mechanism located after said gathering cylindersand operatively associated with the superimposed ribbons to act on thelatter at said spaces between the printed impressions;

means operated in timed relationship with the cyclic operation of saidmechanism for producing a reference pulse at a predetermined point ineach cycle of operation of said mechanism; means for determining foreach of the ribbons an error factor which includes at least the detectedpositional error of the register mark on the respective ribbon in thepresent cycle of operation of said mechanism and the summation of thepositional errors of the register marks on the respective ribbon inprevious cycles of operation;

and correction means operated by said last-mentioned means andoperatively associated with said plurality of rollers and each ribbonindividually to varythe speed of the respective ribbons substantially inaccordance with said error factor which includes the detected positionalerror of the register mark in the present cycle of operation of saidmechanism and the summation of the positional errors of the registermarks on the respective ribbon in previous cycles of operation.

22. A registration control system according to claim 21 wherein saidcorrection means includes means for providing during each cycle ofoperation of said cyclically operated mechanism a series of correctionpulses proportional to the speed of the cyclic operation of saidmechanism and the timing difference between said registration mark pulseand said reference pulse. and means for changing the speed of therespective ribbon in accordance with the number of-said correctionpulses.

23. A registration control system according to claim 22. wherein saidmeans for providing the correction pulses includes a normally closedgate circuit, means for opening said gate circuit in response to eithersaid register mark pulse or said reference pulse and for closing thegate circuit in response to the other of said pulses, and means forgenerating a series of pulses whose frequency is proportional to thespeed of said cyclically operated mechanism and for applying saidlast-mentioned pulses to said gate circuit to pass through the gatecircuit while the latter is open.

24. A registration control system according to claim 23, wherein saidlast-mentioned means comprises a tachometer driven by said cyclicallyoperated mechanism for producing a voltage proportional to the speed ofthe cyclic operation of said mechanism. and a voltage-to-frequencyconverter operated by said tachometer to generate said series of pulsesat a frequency proportional to the voltage produced by the tachometer.

25. A registration control system according to claim 21, and furthercomprising means for varying the timing of said reference pulse withrespect to the cyclic operation of said mechanism in accordance with adetected positional error of one of the gathered ribbons.

26. A registration control system according to claim 21, and whereinsaid last-mentioned means is operative during only certain of theoperating cycles of said mechanism.

27. A registration control system according to claim 21, and furthercomprising:

additional sensing means between said gathering cylinders and saidcyclically operated mechanism for sensing the movement past it'of aregister mark on one of the superimposed ribbons and for'producing aregister mark pulse in response to said sensing of said register mark;and means for comparing the timing of said last-mentioned register markpulse anda fixed phase reference pulse produced in the correspondingcycle of operation of said mechanism to indicate the positional error ofthe gathered ribbons with respect to said mechanism.

28. A registration control system according to claim 21, and furthercomprising means for providing error pulses during each cycle ofoperation of said cyclically operated mechanism, said means fordetermining an error factor including a first counter connected toreceive error pulses corresponding to the detected positional error ofthe register mark on the respective ribbon during the present cycle ofoperation of said mechanism during each cycle of operation and operativeto maintain a count of the summation of all the error pulses forprevious cycles of operation, a second counter for receiving during eachcycle of operation both the count stored in the first counter at the endof the preceding cycle of operation and error pulses corresponding to atleast the detected positional error of the register mark on therespective ribbon for the present cycle of operation, and means forresetting said second counter at the end of each cycle of operation. s

29. A registration control system according to claim 2|. 2! and furthercomprising means operative in accordance with said positional error ofthe gathered ribbons for varying the timing of the reference pulseswhich are compared with the register mark pulses to control theindividual speeds of the respective ribbons.

30. A registration control system for a plurality of printed ribbons,each having printed areas in succession along its length which areseparated by spaces having a register mar therein, said control systemcomprising:

a plurality of pairs of confronting rollers providing controloperatively associated with the web ribbons to urge the latter intosuperimposed relationship;

a cyclically operated mechanism located after said gathering cylindersand operatively associated with the superimposed web ribbons to act onthe latter at said spaces between the printed impressions;

means operated in timed relationship with the cyclic operation of saidmechanism for producing a reference pulse at a predetermined point ineach cycle of operation of said mechanism;

means for comparing the timing of said register mark pulse and saidreference pulse to determine any positional error of the respectiveregister mark on the web ribbon with respect to the cyclic operation ofsaid mechanism;

correction means operated by said last-mentioned means and operativelyassociated with each control nip drive means individually to vary thespeed of the respective control nip as a function of the detectedpositional error of the register mark on the respective ribbon,

additional sensing means between said gathering cylinders and saidcyclically operated mechanism for sensing the movement past it of aregister mark on one of the superimposed web ribbons and for producing aregister mark pulse in response to said sensing of said register mark;and

means for comparing the timing of said last-mentioned register markpulse and a fixed phase reference pulse produced in the correspondingcycle of operation of said mechanism to indicate the positional error ofthe gathered ribbons with respect to said mechanism.

31. A registration control system according to claim 30. and

-further comprising means operative in accordance with said positionalerror of the gathered ribbons for varying the timing of the referencepulses which are compared with the register mark pulses to control theindividual speeds of the respective control nips.

32 A registration control system according to claim 31. and furthercomprising means for'preventing said last-mentioned means from changingthe timing of said last-mentioned reference pulses with respect to thecyclic operation of said further comprising means for preventing thevariation of the timing of said reference pulses with respect to thecyclic r operation of said mechanism except when said positional errorof the'gathered ribbons'exceeds a predetermined value.

p :35, A registration control system for registering a plurality 'ofribbons relative to a cyclically operated mechanism, said systemcomprising means for providing a first reference signal having apredetermined relationship with a cycle of operation otfth' 'emechanism, sensor means for providing a plurality of registrationsignals each'of which is associated with one of the ribbons when theassociated ribbons is in a predetermined position relative to themechanism, first control means for des. testing an, error in theposition of any one of the ribbons relative to the mechanism in responseto a relationship between sai d first reference signal and aregistration signal associated with-,said oneof the ribbons and foreffecting a change in the position of said one of the ribbons relativeto the mechanism in response to the detecting of an error in theposition of said one of the ribbons relative vto the mechanism, meansfor providing a second reference signal having a predeterminedrelationship with the cycle of operation of the mechanism, secondcoptrol means for detecting an error in the position of at leasg one ofthe ribbons relative to the mechanism in responsea relationship betweena registration signal associated with that ribbon and said secondreference signal, apd means for varying the predetermined relationship vbetween said first reference signal and the cycle of operation of themechanism in response to the detection by said second control means ofanerror ofa predetermined magnitude in the position of at least one of theribbons relative to the mechanism to thereby vary the relationshipbetween said first reference signal and said registrationsignals.

36. A registration control system as se't forth in claim 35 wherein saidfirst control 'meansaincludesta plurality control nips each of which isfor operating on an associated one of the ribbons, said sensor meansincludingl'fttst sensor"elements each of which is associated with one'ofthe' ribbons and is operable provide a registration signal which'sa'ijdfirst control means relates to said first referencosignal todetect error in the position of the associated ribbon '-'atelative*tothe mechanism and a second sensor element which is associated with oneof the ribbons at a location along the ribbon which is closer to themechanism than said control nips, said second sensor element beingoperable to provide a registration signal which said second controlmeans relates to said second reference signal to detect error in theposition of the ribbon which said second sensor element is associatedafter this ribbon has passed through an associated one of said controlnips.

37.. A registration system as set forth in claim 36 wherein said firstcontrol means further includes variable speed drive 2 .means operativelyassociated with said control nips for individually controllingthevelocity of the ssociated ribbons at each of said controlnips andcorrection r n ans operatively associated with said variable speed drivemeans to individually vary the speed of said control nips substa n allyin accordance with an error factor equal to where E,, is the detectederror in the position a ribbon in the 1-1 present cycle of operation ofthe mechanism, and k UNITED STATES QFFICE CERTIFICATE OF CORRECTIONPatent No. 3,556,509 Dated January 19, 1971 Inventor(s) James m It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

of the line;

Column l8. line 1, delete "21" second occurrence; and

Column 19 line 12, change "3" to -33-.

Signed and sealed this 27th day of April 1971 (SEAL) Attest:

EDWARD M.FLETCHZER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents FORM PC4050 (10-69) Hun... R,-

1. A registration control system for a web member passing through acontrol nip and from there into a cyclically operated mechanism, saidsystem comprising: variable speed drive means operatively associatedwith the control nip to control its velocity; sensing means operativelyassociated with the web member for sensing any positional error of theadvancing web member with respect to the cyclic operation of saidmechanism; and correction means operatively associated with saidvariable speed drive means to vary the speed of the control nipsubstantially in accordance with an error factor equal to
 2. Aregistration control system according to Claim 1, wherein saidcorrection means comprises a first counter for maintaining a count of asecond counter for receiving a count of 2En during each cycle ofoperation of said cyclically operated mechanism and for receiving thecount stored in said first counter, and means for resetting said secondcounter after each cycle of operation of said cyclically operatedmechanism.
 3. A registration control system for a plurality of printedweb ribbons passing through respective individual control nips and fromthere into superimposed relationship and thereafter into a cyclicallyoperated mechanism, said system comprising: variable speed drive meansoperatively associated individually with the respective control nips tocontrol individually the velocity of each control nip; sensing meansoperatively associated individually with each web ribbon for sensing anypositional error of the advancing ribbon with respect to the cyclicoperation of said mechanism; and correction means operatively associatedwith each variable speed drive means individually to vary the speed ofthe respective control nip substantially in accordance with an errorfactor equal to
 4. A registration control system according to claim 3,wherein said variable speed drive means for each control nip comprises adifferential and a stepping motor for varying the output speed of thedifferential in accordance with the energization of the stepping motor.5. A registration control system according to claim 3, wherein saidcorrection means comprises a first counter for maintaining a count of asecond counter for receiving a count of 2En during each cycle ofoperation of said cyclically operated mechanism and for receiving thecount stored in said first counter, and means for resetting said secondcounter after each cycle of operation of said cyclically operatedmechanism.
 6. A registration control system for a plurality of printedweb ribbons, each having printed areas in succession along its lengthwhich are separated by spaces having a register mark therein, saidcontrol system comprising: A plurality of pairs of confronting rollersproviding control nips for the respective web ribbons; A variable speeddrive means operatively associated individually with each control nip tocontrol the latter''s velocity; Means operatively associatedindividually with each web ribbon ahead of the respective control niptherefor for maintaining a substantially constant tension on said webribbon; sensing means positioned near each control nip for sensing themovement past it of each register mark on the respective web ribbon andfor producing a register mark pulse in response to said sensing of aregister mark; gathering cylinders located after said control nips andoperatively associated with the web ribbons to urge the latter intosuperimposed relationship; a cyclically operated mechanism located aftersaid gathering cylinders and operatively associated with thesuperimposed web ribbons to act on the latter at said spaces between theprinted impressions; means operated in timed relationship with thecyclic operation of said mechanism for producing a reference pulse at apredetermined point in each cycle of operation of said mechanism; meansfor comparing the timing of said register mark pulse and said referencepulse to determine any positional error of the respective register markon the web ribbon with respect to the cyclic operation of saidmechanism; and correction means operated by said last-mentioned meansand operatively associated with each control nip drive meansindividually to vary the speed of the respective Control nipsubstantially in accordance with an error factor equal to
 7. Aregistration control system according to claim 6, and further comprisinga first counter connected to receive En error pulses during each cycleof operation and operative to maintain a count of the summation of allthe error pulses for previous cycles of operation, a second counter forreceiving during each cycle of operation both the count stored in thefirst counter at the end of the preceding cycle of operation and 2Enerror pulses for the present cycle of operation, and means for resettingsaid second counter at the end of each cycle of operation.
 8. Aregistration control system according to claim 7, and further comprisingmeans for passing a series of correction pulses to said correctionmeans, and means for subtracting said correction pulses from the countstored in said second counter.
 9. A registration control systemaccording to claim 8, and further comprising means for blocking saidcorrection pulses from said correction means whenever the count storedin said second counter reaches zero.
 10. A registration control systemaccording to claim 8, wherein said first and second counters receivetheir respective counts during the interval in each cycle of operationwhile said space between successive printed areas on the respectiveribbon is moving past said means for sensing the register mark thereon.11. A registration control system according to claim 10, wherein thecorrection pulses reduce the count stored in said second counter while aprinted area on the respective ribbon is moving past said means forsensing the register mark thereon.
 12. A registration control system fora plurality of printed web ribbons passing through respective individualcontrol nips and from there into superimposed relationship andthereafter into a cyclically operated mechanism, said system comprising:variable speed drive means operatively associated individually with therespective control nips to control individually the velocity of eachcontrol nip; sensing means operatively associated individually with eachweb ribbon near the respective control nip for sensing any positionalerror of the advancing ribbon thereat with respect to the cyclicoperation of said cyclically operated mechanism; correction meanscontrolling each variable speed drive means individually and operable inresponse to said sensing means to vary the speed of the respectivecontrol nip; additional sensing means operatively associated with one ofthe web ribbons near said cyclically operated mechanism for sensing apositional error of the superimposed ribbons with respect to the cyclicoperation of said mechanism; and means operated by said additionalsensing means for varying the operation of said correction means foreach variable speed drive means in accordance with said positional errorof the superimposed web ribbons.
 13. A registration control systemaccording to claim 12, wherein said correction means varies the speed ofthe respective control nip substantially in accordance with an errorfactor equal to
 14. A registration control system according to claim 12,and further comprising means for preventing said last-mentioned meansfrom varying the operation of said correction means except duringcertain cycles of operation of said cyclically operated mechanism.
 15. Aregistration control system acCording to claim 14, and furthercomprising means for preventing said means operated by said additionalsensing means from varying the operation of said correction means exceptwhen said positional error of the superimposed web ribbons exceed apredetermined value.
 16. A registration control system for a pluralityof printed ribbons passing into superimposed relationship and thereafterinto a cyclically operated mechanism, said system comprising: meansoperatively associated individually with the respective ribbons tocontrol individually the velocity of each of the ribbons; sensing meansoperatively associated individually with each ribbon for sensing anypositional error of the advancing ribbon with respect to the cyclicoperation of said mechanism; means for determining for each of theribbons an error factor which includes a summation of the positionalerrors of the respective ribbon in previous cycles of operation of themechanism; and correction means operatively associated with each ribbonindividually for varying the speed of the respective ribbon inaccordance with said error factor which includes a summation of thepositional errors of the respective ribbon in previous cycles ofoperation of said mechanism.
 17. A registration control system accordingto claim 16, wherein each ribbon has a plurality of successive printedareas with spaces therebetween having a registration mark therein, andsaid sensing means for each ribbon comprises: means for sensing thepassing of a register mark on the respective ribbon and for producing aregister mark pulse in response thereto; means operated in response tothe cyclic operation of said mechanism for producing a reference pulseat a predetermined point in the latter''s cycle of operation; and andmeans for determining the magnitude of the detected positional error ofeach ribbon for each cycle of operation said mechanism in accordancewith the time difference between said register mark pulse and saidreference pulse.
 18. A registration control system according to claim17, wherein said last-mentioned means comprises a normally closed gatecircuit, means for opening said gate circuit in response to either saidregister mark pulse or said reference pulse and for closing the gatecircuit in response to the other of said pulses, and means for producinga series of pulses whose frequency is proportional to the speed of saidcyclically operated mechanism and for applying said last-mentionedpulses to said gate circuit to pass through the gate circuit while thelatter is open.
 19. A registration control system according to claim 18,wherein said means for producing a series of pulses comprises atachometer driven by said cyclically operated mechanism for producing avoltage proportional to the speed of the cyclic operation of saidmechanism, and a voltage-to-frequency converter operated by saidtachometer to generate said series of pulses at a frequency proportionalto the voltage produced by the tachometer.
 20. A registration controlsystem according to claim 16, wherein said error factor further includesat least the detected positional error of the respective ribbon in thepresent cycle of said mechanism, and said correction means includes afirst counter for maintaining a count of the summation of the positionalerrors of the respective ribbon in previous cycles of operation of saidmechanism, a second counter for receiving a count of at least thedetected positional error of the respective ribbon in the present cycleof said mechanism during each cycle of operation of said cyclicallyoperated mechanism, and means for resetting said second counter aftereach cycle of operation of said cyclically operated mechanism.
 21. Aregistration control system for a plurality of printed ribbons, eachhaving printed areas in succession along its length which are separatedby spaces having a register mark therein, said control systemcomprising: a plurality of rollers operatively assoCiated with eachribbon to control the velocity of the associated ribbon; sensing meanspositioned near each of the respective ribbons for sensing the movementpast it of each register mark on the respective ribbon and for producinga register mark pulse in response to said sensing of a register mark;gathering cylinders located after said rollers and operativelyassociated with the ribbons to urge the latter into superimposedrelationship; a cyclically operated mechanism located after saidgathering cylinders and operatively associated with the superimposedribbons to act on the latter at said spaces between the printedimpressions; means operated in timed relationship with the cyclicoperation of said mechanism for producing a reference pulse at apredetermined point in each cycle of operation of said mechanism; meansfor determining for each of the ribbons an error factor which includesat least the detected positional error of the register mark on therespective ribbon in the present cycle of operation of said mechanismand the summation of the positional errors of the register marks on therespective ribbon in previous cycles of operation; and correction meansoperated by said last-mentioned means and operatively associated withsaid plurality of rollers and each ribbon individually to vary the speedof the respective ribbons substantially in accordance with said errorfactor which includes the detected positional error of the register markin the present cycle of operation of said mechanism and the summation ofthe positional errors of the register marks on the respective ribbon inprevious cycles of operation.
 22. A registration control systemaccording to claim 21 wherein said correction means includes means forproviding during each cycle of operation of said cyclically operatedmechanism a series of correction pulses proportional to the speed of thecyclic operation of said mechanism and the timing difference betweensaid registration mark pulse and said reference pulse, and means forchanging the speed of the respective ribbon in accordance with thenumber of said correction pulses.
 23. A registration control systemaccording to claim 22, wherein said means for providing the correctionpulses includes a normally closed gate circuit, means for opening saidgate circuit in response to either said register mark pulse or saidreference pulse and for closing the gate circuit in response to theother of said pulses, and means for generating a series of pulses whosefrequency is proportional to the speed of said cyclically operatedmechanism and for applying said last-mentioned pulses to said gatecircuit to pass through the gate circuit while the latter is open.
 24. Aregistration control system according to claim 23, wherein saidlast-mentioned means comprises a tachometer driven by said cyclicallyoperated mechanism for producing a voltage proportional to the speed ofthe cyclic operation of said mechanism, and a voltage-to-frequencyconverter operated by said tachometer to generate said series of pulsesat a frequency proportional to the voltage produced by the tachometer.25. A registration control system according to claim 21, and furthercomprising means for varying the timing of said reference pulse withrespect to the cyclic operation of said mechanism in accordance with adetected positional error of one of the gathered ribbons.
 26. Aregistration control system according to claim 21, and wherein saidlast-mentioned means is operative during only certain of the operatingcycles of said mechanism.
 27. A registration control system according toclaim 21, and further comprising: additional sensing means between saidgathering cylinders and said cyclically operated mechanism for sensingthe movement past it of a register mark on one of the superimposedribbons and for producing a register mark pulse in response to saidsensing of said register mark; and means for comparing the timing ofsaid last-menTioned register mark pulse and a fixed phase referencepulse produced in the corresponding cycle of operation of said mechanismto indicate the positional error of the gathered ribbons with respect tosaid mechanism.
 28. A registration control system according to claim 21,and further comprising means for providing error pulses during eachcycle of operation of said cyclically operated mechanism, said means fordetermining an error factor including a first counter connected toreceive error pulses corresponding to the detected positional error ofthe register mark on the respective ribbon during the present cycle ofoperation of said mechanism during each cycle of operation and operativeto maintain a count of the summation of all the error pulses forprevious cycles of operation, a second counter for receiving during eachcycle of operation both the count stored in the first counter at the endof the preceding cycle of operation and error pulses corresponding to atleast the detected positional error of the register mark on therespective ribbon for the present cycle of operation, and means forresetting said second counter at the end of each cycle of operation. 29.A registration control system according to claim 21, 21 and furthercomprising means operative in accordance with said positional error ofthe gathered ribbons for varying the timing of the reference pulseswhich are compared with the register mark pulses to control theindividual speeds of the respective ribbons.
 30. A registration controlsystem for a plurality of printed ribbons, each having printed areas insuccession along its length which are separated by spaces having aregister mark therein, said control system comprising: a plurality ofpairs of confronting rollers providing control nips for the respectiveweb ribbons; a variable speed drive means operatively associatedindividually with each control nip to control the latter''s velocity;means operatively associated individually with each web ribbon ahead ofthe respective control nip therefor for maintaining a substantiallyconstant tension on said web ribbon; sensing means positioned near eachcontrol nip for sensing the movement past it of each register mark onthe respective web ribbon and for producing a register mark pulse inresponse to said sensing of a register mark; gathering cylinders locatedafter said control nips and operatively associated with the web ribbonsto urge the latter into superimposed relationship; a cyclically operatedmechanism located after said gathering cylinders and operativelyassociated with the superimposed web ribbons to act on the latter atsaid spaces between the printed impressions; means operated in timedrelationship with the cyclic operation of said mechanism for producing areference pulse at a predetermined point in each cycle of operation ofsaid mechanism; means for comparing the timing of said register markpulse and said reference pulse to determine any positional error of therespective register mark on the web ribbon with respect to the cyclicoperation of said mechanism; correction means operated by saidlast-mentioned means and operatively associated with each control nipdrive means individually to vary the speed of the respective control nipas a function of the detected positional error of the register mark onthe respective ribbon, additional sensing means between said gatheringcylinders and said cyclically operated mechanism for sensing themovement past it of a register mark on one of the superimposed webribbons and for producing a register mark pulse in response to saidsensing of said register mark; and means for comparing the timing ofsaid last-mentioned register mark pulse and a fixed phase referencepulse produced in the corresponding cycle of operation of said mechanismto indicate the positional error of the gathered ribbons with respect tosaid mechanism.
 31. A registration control system according to claim 30,and further comprising means operative in accordance with saidpositional error of the gathered ribbons for varying the timing of thereference pulses which are compared with the register mark pulses tocontrol the individual speeds of the respective control nips.
 32. Aregistration control system according to claim 31, and furthercomprising means for preventing said last-mentioned means from changingthe timing of said last-mentioned reference pulses with respect to thecyclic operation of said mechanism except when said positional error ofthe gathered ribbons exceeds a predetermined value.
 33. A registrationcontrol system according to claim 31, and further comprising means forpreventing said last-mentioned means from varying the timing of saidreference pulses except during certain cycles of operation of saidcyclically operated mechanism.
 34. A registration control systemaccording to claim 3, and further comprising means for preventing thevariation of the timing of said reference pulses with respect to thecyclic operation of said mechanism except when said positional error ofthe gathered ribbons exceeds a predetermined value.
 35. A registrationcontrol system for registering a plurality of ribbons relative to acyclically operated mechanism, said system comprising means forproviding a first reference signal having a predetermined relationshipwith a cycle of operation of the mechanism, sensor means for providing aplurality of registration signals each of which is associated with oneof the ribbons when the associated ribbons is in a predeterminedposition relative to the mechanism, first control means for detecting anerror in the position of any one of the ribbons relative to themechanism in response to a relationship between said first referencesignal and a registration signal associated with said one of the ribbonsand for effecting a change in the position of said one of the ribbonsrelative to the mechanism in response to the detecting of an error inthe position of said one of the ribbons relative to the mechanism, meansfor providing a second reference signal having a predeterminedrelationship with the cycle of operation of the mechanism, secondcontrol means for detecting an error in the position of at least one ofthe ribbons relative to the mechanism in response to a relationshipbetween a registration signal associated with that ribbon and saidsecond reference signal, and means for varying the predeterminedrelationship between said first reference signal and the cycle ofoperation of the mechanism in response to the detection by said secondcontrol means of an error of a predetermined magnitude in the positionof at least one of the ribbons relative to the mechanism to thereby varythe relationship between said first reference signal and saidregistration signals.
 36. A registration control system as set forth inclaim 35 wherein said first control means includes a plurality controlnips each of which is for operating on an associated one of the ribbons,said sensor means including first sensor elements each of which isassociated with one of the ribbons and is operable provide aregistration signal which said first control means relates to said firstreference signal to detect error in the position of the associatedribbon relative to the mechanism and a second sensor element which isassociated with one of the ribbons at a location along the ribbon whichis closer to the mechanism than said control nips, said second sensorelement being operable to provide a registration signal which saidsecond control means relates to said second reference signal to detecterror in the position of the ribbon which said second sensor element isassociated after this ribbon has passed through an associated one ofsaid control nips.
 37. A registration system as set forth in claim 36wherein said first control means further includes variable speed drivemeans operatively associated with said control nips for individuallycontrolling the velocity of the associated ribbons at each of saidcontrol nips and correction means operatively associated with saidvariable speed drive means to individually vary the speed of saidcontrol nips substantially in accordance with an error factor equal towhere En is the detected error in the position a ribbon in the presentcycle of operation of the mechanism, and is the summation of thepositional errors of a ribbon in previous cycles of operation of themechanism.